NameError: variable @list-group-bg is undefined in /Users/haifeng/IT/01_Study/github_projects/js_framework/public/js/lib/bootstrap/3.0.0/css/list-group.less on line 23, column 21:
22   margin-bottom: -1px;
23   background-color: @list-group-bg;
24   border: 1px solid @list-group-border;

